1. Field of the Invention
The present invention relates to a damping arrangement for a gliding board, in particular for an alpine ski, as well as for gliding boards of other types, such as snowboards and Nordic skis, the latter including, e.g., cross-country skis. In the following description, unless specifically described otherwise, reference made to a ski is for the purpose of convenience and not for the purpose of limiting the scope of the invention from gliding boards as mentioned above. The invention relates more particularly to an improvement to a damping arrangement of the aforementioned type, as well as to a ski, or other gliding board, equipped with such a device or arrangement. The method is also directed to a method of manufacturing such a gliding board.
2. Description of Background and Other Information
It is known to make the body of a ski to have a more or less flexible structure.
Various types of skis are known, and there are numerous variations among them. Such skis are comprised of an elongated beam, the front end of which is curved upward to constitute the shovel, the rear end also being curved upward more slightly to constitute the tail.
Currently available skis generally have a composite structure in which various materials are combined, so that each of them cooperates with the others in an optimal manner, particularly in terms of the distribution of mechanical stresses during use of the ski. Thus, the structure generally includes peripheral protective elements, internal reinforcement elements to resist flexion and torsion forces, as well as a core. These elements are assembled by gluing or by injection molding, the assembly being carried out generally under heat in a mold having the final shape of the ski, with a front portion sharply raised into a shovel, a rear portion slightly raised into a tail, and a cambered central portion.
In spite of their desire to make high quality skis, manufacturers have not, to date, produced a highly efficient ski that performs satisfactorily under all conditions of use.
Currently available skis have a number of disadvantages, particularly that of poor performance when oscillations are produced by vibrations or flexing of the ski. Indeed, persistent vibrations cause a loss of adherence of the ski to the snow or terrain and, therefore, result in poor steering of the ski, i.e., a lessened control of the ski. Therefore, it is very important to damp the vibrations; and some solutions have been proposed, such as those disclosed in patent documents DE 297 09 403, EP 0 521 272, EP 0 733 386, and U.S. Pat. No. 5,332,252, for example. However, the effects of these damping devices are in fact quite minor and imperceptible to the skier.
Document DE 297 09 403 discloses a gliding board with a damping arrangement comprised of a channel in which a friction piston slides freely. The friction piston can be comprised of parallelepipedic or cylindrical rods. In both cases, the friction piston has a certain thickness which is greater than a third of the total thickness of the ski. This substantial thickness of the friction elements in relation to the total thickness of the ski causes a substantial alteration in the characteristics of the ski, in particular the flexion and torsion characteristics. In addition, the excessive thickness of the damping arrangement in relation to the total thickness of the ski is such that the damping arrangement is close to the neutral plane of the ski. When the beam of the ski is subject to upward flexion, the upper portion of the beam is subject to compressive stresses, whereas the lower portion of the beam is subject to tensile stresses. The neutral plane of the beam corresponds to an imaginary surface comprised of all points of the beam which are subject neither to tension nor to compression. The damping arrangement of a gliding board is more efficient as it is farther from the neutral plane thereof. In the case of the ski disclosed in DE 297 09 403, this characteristic is far from extant.
The documents EP 0 521 272 and US 5,332,252 disclose a ski having a damping arrangement comprised of a flexion blade connected to the ski via a friction device. Such a system has numerous disadvantages, in particular those relating to the damping arrangement being separate from the structure of the ski or at least outside of the reinforcing layers of the ski structure. The mounting of the damping arrangement on the ski is carried out mainly after the primary manufacturing stage of the ski, i.e., after the molding of the ski, such as by injection. In addition, the mounting on the outer surface of the ski considerably hinders the decoration thereof and especially limits possibilities for the design and external appearance of the ski.
The document EP 0 733 386 discloses a ski having a damping arrangement comprised of a plurality of blades positioned one on top of another. The damping arrangement is distinct from the remainder of the ski and is comprised of a closed box in which the blades and the friction layers form a stack, the box being inserted between the upper reinforcement and the top of the ski, i.e., the top of the ski being comprised of the protective and decorative layer. Here again is a damping arrangement which considerably modifies the mechanical characteristics of the ski, inasmuch as the damping device is heavy and thick.
The documents EP 0 966 992 and U.S. Pat. No. 6,237,932 disclose a ski, the sides of which are provided with damping elements for damping only the specific unwanted vibrations that propagate between the running edges and the top of the ski. These damping elements are made of flexible or viscoelastic material and function by means of compression.